In December 2016, a critical part of Curiosity’s drill stopped working. Two stabilizers flanking the drill bit steady the drill against its target rock. You can see how the setup looks below.
A motor that lets the drill bit extend and retract between the pair of stabilizers stopped working. But the Curiosity team wasn’t about to give up. To quote everyone’s favorite farming movie, they had to “science the shit out of this.” Long hours tinkering with a replica of Curiosity back on Earth led to a solution. Curiosity would drill on Mars much like we do on Earth – freehand.
A force sensor originally designed to stop Curiosity’s arm if it jolted too much is now used to give the rover a crucial sense of touch. Now, Curiosity can make adjustments on the fly to prevent the drill bit from moving sideways or getting stuck. Just like you or me would do when drilling into a wall.
“We’re now drilling on Mars more like the way you do at home,” said Steven Lee, who serves as deputy project manager at NASA’s Jet Propulsion Laboratory. “Humans are pretty good at re-centering the drill, almost without thinking about it. Programming Curiosity to do this by itself was challenging – especially when it wasn’t designed to do that.”
Curiosity can drill to a depth of 6 centimeters, but the test hole drilled earlier this week was about one centimeter deep.
Doug Klein, one of Curiosity’s sampling engineers, explains what’s next for Curiosity. “Next, we have to drill a full-depth hole and demonstrate our new techniques for delivering the sample to Curiosity’s two onboard labs.”
With the drill always in its extended position, the arm can’t access a device called Collection and Handling for In-Situ Martian Rock Analysis, or CHIMRA. This device sieves and delivers the powder sample to Curiosity’s instruments.
The folks working on Curiosity had to develop a new method for delivering powder samples to the rover’s instruments. NASA compares it to tapping salt out of a shaker. The rover will shake powder from its drill bit. Testing on Earth shows it works, but that’s also with Earth’s gravity and atmosphere. Another hole will soon be drilled, and if enough powder can be collected, will test this new method.
If everything goes smoothly, Curiosity’s drill will be back in the game as the team looks to gather enticing samples from the Vera Rubin Ridge area. The upper ridge of this area contains red rocks rich in hematite. That’s an iron oxide mineral that forms when water is around. Samples from these rocks could help explain how they formed and shed more light on Mars’ wet past.